Transcript Document

Mining and Petroleum Training Service
Basics of
Equipment Guarding
Presented by David Spann
Presentation Developed by Rene Azzara
Basics of Machine Safeguarding
Crushed hands and arms, severed fingers, blindness the list of possible machinery-related injuries is as
long as it is horrifying.
There seem to be as many hazards created by moving
machine parts as there are types of machines.
Safeguards are essential for protecting workers from
needless and preventable injuries.
A good rule to remember is:
Any machine part, function, or process which
many cause injury must be safeguarded.
When the operation of a machine or accidental
contact with it can injure the operator or others
in the vicinity, the hazards must be either
controlled or eliminated.
Tolerable Risk:
"risk that is accepted for a given task and
hazard combination"
- as described in ANSI B11.TR3
Following an organized and logical approach, risk
assessment and risk reduction can achieve a
tolerable risk.
Risk Assessment Process
Gather Equipment
Specifications
Determine Equipment
Limitations
Identify Equipment
Hazards and Task Hazards
Use Limitations
Catastrophic: Permanent Disabling
Serious: Severe Disabling
Moderate: Significant Disabling
Estimate Risk
& Probability
Minor: Sligh Disabling
Unlikely, Not Likely to Occur
Remote: Very Unlikely
Time Limitations
Environment Limitations
Interface Limitations
Very Likely to Occur
Likely, May Occur
Space Limitations
Determine Whether Risk
Is Tolerable
If Untolerable,
Risk Reduction Measures
Must Be Implemented
Hazard Reduction Activities
Supportive
Use PPE
Incorporate
Administrative Controls
Incorporate
Safeguarding Technologies
Primary
Eliminate and Reduce
Hazards by Design
Where to begin
• Know how to use the machine safely before operating.
• Have you reviewed the owner's manual? It will provide
operating, repairing, lubricating and fuel information.
• Are the Warning Decals in place?
• Are the machine guards properly placed and in good condition?
• Are electrical lines damage free?
• Are air and hydraulic lines in good condition and not leaking?
• Is the setup a proper setup?
• Is the area around the machines orderly?
Safety begins before you
even start the equipment!
Personal Protection:
• Wear PPE, such as goggles, safety shoes
and leather gloves.
• Long hair should be tied back or tucked
under to avoid getting caught in machinery.
• Avoid wearing jewelry.
Machine Maintenance Checklist for Safety:
Keep machines repaired, lubricated and adjusted.
Clean up excess lubricants.
Clearly mark control switches and valves that
control machines.
Check machines for emergency stop switches;
they should be located on or near the machine so
the machine can be turned off quickly if a
malfunction occurs.
Dangerous moving parts in
three basic areas require safeguarding:
Power transmission apparatus
All components of the mechanical system which transmit energy
to the part of the machine performing the work. These components
include flywheels, pulleys, belts, connecting rods, couplings, cams,
spindles, chains, cranks, and gears.
Other moving parts
All parts of the machine which move while the machine is working.
These can include reciprocating, rotating, and transverse moving
parts, as well as feed mechanisms and auxiliary parts of the
machine.
The Point of Operation
The point where work is performed on the material, such as
cutting, shaping, boring, or forming of stock.
Hazardous Mechanical Motions and Actions
The basic types of hazardous mechanical motions and actions are:
Motions
• rotating (including in-running nip points)
• reciprocating
• transversing
Actions
• cutting
• punching
• shearing
• bending
Warnings and training are
least effective because
people will always make mistakes!
Some guards are designed
based on hand speed
The human hand can move at
63 inches per second!
Example: A device located 2 inches from a
grinder must be able to sense the hand and
stop the grinder in under 0.03 seconds.
[T=2(in)/63(in/s)=.032s]
Types of guarding devices
Presence Sensing (photo electric light curtain)
Pullback - Restraint - Gates or Covers
Safety Controls
Others: distance and automatic systems
Be Aware of Nip Points:
Hazardous spots where loose clothing or body parts
could be caught and squeezed in rotating parts.
All pulleys, belts, sprockets and chains, flywheels, shafting
and shaft projections, gears, and couplings, or other rotating
or reciprocating parts.
Nip Points:
Rotating Dangers
• clothing
• jewelry
• hair
• body parts
Do not wear gloves around reciprocating or rotating machine parts.
Note: A nip point entry permit system is
intended for observation of hazardous
machinery while at a safe distance.
It is not a "Permit to Work" in a nip point
zone.
Permit to Work activity must only be
undertaken with the machine shut down
and locked out.
Protecting Hands and Fingers Guide:
• Identify the pinch points on mechanically moved loads, lowered loads and metal drums.
• Know when to wear gloves. Sometimes gloves can present a danger!
• Allow rotating parts to come to a stop before working on them.
• Use a tapered punch or other appropriate tool to align the holes in parts.
• Rings should not be worn when operating or repairing machinery.
• Remove fuses with fuse removers, not fingers.
• Do not test the temperatures of gases, liquids, or solids with hands. Reflex damage can
occur immediately.
• Keep grinder tool rests adjusted to 1/8 inch gap or less.
• Handle sharp or pointed tools (hatchets, chisels, punches, awls, knives, pitch forks and
machine blades) carefully.
• Perform maintenance only when tools or machinery are not in operation.
• If guards are removed to perform maintenance, replace immediately after servicing.
Reciprocating motions
may be hazardous because, during the
back-and-forth or up-and-down motion,
a worker may be struck by or caught
between a moving and a stationary
part.
Transverse motion (movement
in a straight, continuous line) creates
a hazard because a worker may be
struck or caught in a pinch or shear
point by the moving part.
More Safety Considerations
Never step across a rotating power shaft.
Equipment operators should wear close-fitting clothes and
slip-resistant footwear. Rotating parts catch loose clothing
easily.
Never allow children around the equipment or work area.
Machinery Maintenance and Repair
Good maintenance and repair procedures contribute
significantly to the safety of the maintenance crew as
well as that of machine operators.
In addition to guarding, you need to understand:
LOTO - Lockout/Tagout (aka)
CHE - Control of Hazardous Energy
In shops where several maintenance persons might be working on the
same machine, multiple lockout devices accommodating several
padlocks are used. The machine cannot be reactivated until each
person removes his or her lock. As a matter of general policy, lockout
control is gained by the procedure of issuing personal padlocks to each
maintenance or repair person; no one but that person can remove the
padlock, thereby each worker controls the power systems.
Whenever machines or equipment are
serviced,
there are hazards encountered by the employees
performing the servicing or maintenance which are
unique to the repair or maintenanceprocedures being
conducted.
These hazards may exist due to the failure of the
employees doing the servicing or maintenance to stop
the machine being worked on.
Even if the machine has been stopped, the machine
can still be hazardous due to the possibility of the
machine becoming reenergized or restarting.
Guards
Guards are barriers which prevent
access to dangerous areas.
There are four general types of guards:
Fixed - A fixed guard is a permanent part of the machine.
Interlocked - When this type of guard is opened or removed, the tripping
mechanism and/or power automatically shuts off or disengages, and the
machine cannot cycle or be started until the guard is back in place.
Adjustable - Adjustable guards are useful because they allow flexibility in
accommodating various sizes of stock.
Self-Adjusting - The openings of these barriers are determined by the
movement of the stock. Self-adjusting guards offer different degrees of
protection.
Guard Construction
Today many builders of single-purpose machines provide point-ofoperation and power transmission safeguards as standard equipment.
However, not all machines in use have built-in safeguards
provided by the manufacturer!
Guards designed and installed by the builder offer
two main advantages:
• They usually conform to the design and function of the
machine.
• They can be designed to strengthen the machine in some
way or to serve some additional functional purposes.
Be wary of older
equipment!
Inspect older equipment, and if
necessary upgrade machinery to
current standards.
Lock out or block moving machinery
against motion before working nearby
unless all pulleys and pinch points
are guarded or located where persons
can not contact them.
Guard pinch points on conveyor
pulleys
Establish and enforce policies that
prohibit work or travel near
unguarded machinery components.
A conveyor attendant with 5 years mining
experience was fatally injured at an open
pit copper operation. The victim became
entangled in a tripper conveyor pulley.
User-built guards are sometimes necessary for a variety
of reasons. They have these advantages:
•
Often, with older machinery, they are the only practical
safeguarding solution.
•
They may be the only choice for mechanical power transmission
apparatus in older plants, where machinery is not powered by
individual motor drives.
•
They permit options for point-of-operation safeguards when skilled
personnel design and make them.
•
They can be designed and built to fit unique and even changing
situations.
•
They can be installed on individual dies and feeding mechanisms.
•
Design and installation of machine safeguards by plant personnel
can help to promote safety consciousness in the workplace.
User-built guards also have
disadvantages:
• User-built guards may not conform
well to the configuration and
function of the machine.
• There is a risk that user-built guards
may be poorly designed or built.
• Intended to be installed at
some point, yet never were.
Additional considerations when building
a guard:
•
Does the design, construction, selection of materials and guard
installation prevent contact with all moving machine part hazards?
•
Does the guard provide protection by itself,and not rely on visual or
tactile awareness of a hazard, administrative controls or procedures
such as warnings, signs, lights, training, supervision or PPE?
•
Are the guard materials, fastening methods, and construction suitable
to withstand the wear, corrosion, vibration and shock of normal
operations?
•
If drive belts inside a guard fail, will the whipping action of broken
belts be contained?
•
Is the guard recognizable as a guard?
•
Is the guard installed securely?
Ergonomic Considerations of Machine Safeguarding
Consider worker stress and fatigue when designing.
Employees may defeat guarding if it is difficult to remove and
replace easily.
Design Considerations:
–
–
–
–
–
Lightweight, without being flimsy
Can be handled by one person
Access doors or tops
Guards with rollers or wheels
Screen that allows operator visual access; also allows
operator to rinse off machinery
– Design so hands and tools cannot fit thru screen
Machine Safety Responsibilities
Management
Ensure all machinery is properly guarded
Supervisors
Train employees on specific guard rules in
their areas; Ensure machine guards
remain in place and are functional;
Immediately correct machine guard
deficiencies
Employees
Do not remove guards unless machine is
locked and tagged; Report machine guard
problems to supervisors immediately;
Do not operate equipment unless
guards are in place
Proper training should address:
• Hazards associated with particular machines
• How the safeguards provide protection and the
hazards for which they are intended
• How and why to use the safeguards
• How and when safeguards can be removed and
by whom
• What to do if a safeguard is damaged, missing, or
unable to provide adequate protection
Deaths attributed to
Inadequate Guarding
from MSHA files
On July 21, 2005, a 31-year old plant operator with two years mining
experience was fatally injured at a sand and gravel operation.
The victim made a splice on a conveyor belt and was making
adjustments to the belt.
He was found
entangled in the
tail pulley of the
conveyor.
On February 7, 2002, a 37-year-old male laborer (the victim) was
fatally injured when he became caught between a conveyor belt
and an idler pulley of a rock crushing machine.
The victim's job consisted of sweeping and shoveling
the area around the rock-crushing machine.
Approximately 20 minutes after the victim
arrived at work he was found underneath
the rock crushing machine with his
arm caught between a conveyor belt
and an idler pulley.
The victim was caught by one of the rock crushing machine's conveyor belts and
an idler pulley. The location of the victim was underneath the machine near the
electrical panel.
What steps did the
investigator note that
should have been taken
that would have
prevented this fatality?
• Hazard analysis of equipment prior to use.
• Employee task training.
• Proper guarding.
• Installation of pull cable emergency stops that surrounds the entire
machine's perimeter instead of intermittently placed push buttons.
Does the idler present a
significant hazard?
No
Yes
Is a person likely to get
close to the idler roller
face?
No
Yes
Is the nip point directly
accessible?
No
Yes
An effective guard is required
On June 17, 2005, a 32-year-old equipment operator/mechanic with
5 years mining experience was fatally injured at a sand and gravel
operation. The victim was removing toggle seat wedge bolts so
that the broken pitman toggle seat could be replaced.
The safety pins, provided by the manufacturer:
- had not been installed
- no steps had been taken to block/secure this
component against hazardous motion.
The pitman assembly shifted and fatally pinned
the victim against the crusher framework.
On November 23, 2003, a 44-year-old company vice president
with 2 years mining experience was fatally injured at a crushed
stone operation.
The victim was using a steel bar to
dislodge a blockage in an
impact crusher. The bar contacted
a moving crusher component
causing it to be propelled and
strike the victim's neck.
The accident occurred because
the procedures used to dislodge
the blockage of rock were
inadequate.
When the blockage occurred, the victim failed to deenergize
and lock out the crusher before attempting to dislodge the rock.
Lesson: Deenergize and lockout equipment.
Never attempt to remove jammed material while machinery is in
operation.
Shut down, isolate, and block all forms of hazardous energy
before performing machine maintenance.
Do not allow employees to position themselves directly over the
intake of a horizontal impactor while it is actively crushing rock.
Viewing decks should be designed and installed where worker's
can safely access the equipment to observe operation.
The worker had reversed his truck up
to the primary hopper in order to
discharge a load of quarried material.
He then walked to the rear of his truck,
before falling into the hopper.
In order to discharge the load, it was
not necessary to leave the truck. It is
unknown why the driver did so.
Nothing can protect you from senseless acts.
Lock out before servicing
As he was oiling a moving conveyor, a worker's pant leg became entangled
in the part of the conveyor, causing his right foot to be dragged in and
crushed between the head sprocket and the side of the conveyor.
His right leg had to be amputated
below his knee.
The worker usually oiled the
conveyor from a relatively safe
position from underneath the
conveyor.
For some reason, on this day,
he decided to oil the conveyor
from an unstable position above
the conveyor without locking out.
His pant legs also hung down
below his boots.
Lesson: Follow task procedures every time!
Work safely around guardrails
A machine tender was found pinned in the ingoing nip point of a press.
He died from massive crush injuries. There was no witness to this
accident. Guardrails were in place around the machine.
It is unclear how the victim fell into the nip point of the press.
He may have been reaching into or over top of one of the guardrails.
Lesson: Never reach through
or over top of a guardrail of
any machinery.
Safe work practices:
Do not defeat guards and place body
parts, tools or pry bars in equipment
that is not deenergized or LOTO.
Develop and follow written procedures for checking the
well-being of a worker working alone or in isolation, including
establishingcontact at predetermined intervals and at the end
of the shift.
•
Ensure that miners receive task training prior to allowing them to
perform maintenance or repair on machinery or equipment.
•
Discuss the work procedures, including all possible hazards ( Risk
Assessment ) and ensure the manufacturer's recommendations are
followed for all repair work.
•
Before working on equipment, lock-out the power and block
equipment components against all possible motion/movement
resulting from a sudden release of energy.
•
Make sure you have the proper AUTHORITY to deenergize or lock-out
equipment before proceeding. Shutting off power may shut down
production in other area’s and create safety hazards to unsuspecting
individuals.
•
If potential hazards or prescribed procedures are unclear, DO NOT
proceed until all safety concerns are adequately resolved.
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